To produce an LED (Light Emitting Diode) or an electronic device with a compound semiconductor such as GaN or SiC, an epitaxial growth technique that enables to grow a monocrystalline thin film on a monocrystalline substrate is used.
In a film formation device used in the epitaxial growth technique, a wafer is, for example, placed inside of a film formation chamber kept at a normal pressure or a reduced pressure. When a gas as a material for film formation is supplied into the film formation chamber while the wafer is heated, a pyrolysis reaction and a hydrogen reduction reaction of the material gas occur on a surface of the wafer, which grows an epitaxial film on the wafer.
To deposit a high-quality film with a uniform thickness and a uniform quality on the wafer, the temperature of the wafer needs to be accurately controlled. For this purpose, the temperature of the wafer is measured using a radiation thermometer and a heating unit is controlled (for example, see JP-A 2006-90978).
However, if a thin film that is transparent to a wavelength measured by the radiation thermometer is deposited on the wafer, the emissivity of the measurement wavelength of the radiation thermometer changes due to thin-film interference of the thin film. A temperature detected by the radiation thermometer thus changes depending on the film thickness even when the wafer temperature is constant, which prevents the wafer temperature from being measured accurately. Accordingly, a temperature feedback control to control a heater output based on the detected wafer temperature cannot be achieved and thus a control on the wafer temperature is difficult.
An object of the present invention is to provide a vapor phase growth method and a vapor phase growth device capable of executing a high-accuracy temperature control also when a thin film that causes the thin-film interference is deposited on a substrate.